I. Field
Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to methods and apparatus for repeating uplink synchronization in time division-synchronous code division multiple access (TD-SCDMA) networks.
II. Background
Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the Universal Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP). The UMTS, which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband-Code Division Multiple Access (W-CDMA), Time Division-Code Division Multiple Access (TD-CDMA), and Time Division-Synchronous Code Division Multiple Access (TD-SCDMA). For example, China is pursuing TD-SCDMA as the underlying air interface in the UTRAN architecture with its existing GSM infrastructure as the core network. The UMTS also supports enhanced 3G data communications protocols, such as High Speed Downlink Packet Data (HSDPA), which provides higher data transfer speeds and capacity to associated UMTS networks.
As the demand for mobile broadband access continues to increase, research and development continue to advance the UMTS technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications.
The China Communications Standard Association (CCSA) has published a series of TDD-based 3G standards for TD-SCDMA. In TD-SCDMA systems, the user equipment (UE) needs to perform a random access procedure as the first procedure to contact the network for an uplink (UL) operation. The UL synchronization and random access procedure is defined in the CCSA standards YD/T 1371.5-2008 Technical requirements for Uu Interface of 2 GHz TD-SCDMA Digital Cellular Mobile Communication Network Physical Layer Technical Specification Part 5: Physical Layer Procedure.
It would be preferable to provide additional UL synchronization and random access procedures to the existing system.